C₃N₄ photocatalyst powders have generally been synthesized with a solid-state (SS) method, which formed a graphitic feature with tri-s-triazine (C₆N₇) units as elementary building blocks. The present work reports a solvothermal (ST) synthesis, in which the yellow powders were obtained as low as 150-220 °C using cyanuric chloride (C₃N₃Cl₃) and sodium azide (NaN₃) as the starting materials and acetonitrile as the solvent. X-ray diffraction analyses showed that the crystalline structure of ST samples changed from pseudocubic-C₃N₄ to beta-C₃N₄ with increasing the solvothermal temperature, and powders obtained from SS method displayed a graphitic-C₃N₄ structure with diffraction angles at ca. 13.1° and 27.5°. The two distinct diffraction angles represented (100) plane of tri-s-triazine units and (002) plane of stacking of the conjugated aromatic system, respectively. UV-Vis absorbance spectra showed that the band gap of SS was estimated to be 2.6 eV, and that of ST samples were estimated to be 1.9 to 2.45 eV, varied with solvothermal tempearture. To evaluate the visible-light-responded photocatalytic activity of the samples, degradation of methylene orange dyes was conducted using a 200 W Xenon lamp. ST samples showed a higher photocatalytic activity on degradation of methylene orange, which can be attributed to its larger light absorbance in the visible regime compared to that of SS ones.